Silver Nanowires-Based Flexible Gold Electrode Overcoming Interior Impedance of Nanomaterial Electrodes.

In the development of nanomaterial electrodes for improved electrocatalytic activity, much attention is paid to the compositions, lattice, and surface morphologies. In this study, a new concept to enhance electrocatalytic activity is proposed by reducing impedance inside nanomaterial electrodes. Gold nanodendrites (AuNDs) are grown along silver nanowires (AgNWs) on flexible polydimethylsiloxane (PDMS) support. The AuNDs/AgNWs/PDMS electrode affords an oxidative peak current density of 50 mA cm-2 for ethanol electrooxidation, a value ≈20 times higher than those in the literature do. Electrochemical impedance spectroscopy (EIS) demonstrates the significant contribution of the AgNWs to reduce impedance. The peak current densities for ethanol electrooxidation are decreased 7.5-fold when the AgNWs are electrolytically corroded. By in situ surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) simulation, it is validated that the ethanol electrooxidation favors the production of acetic acid with undetectable CO, resulting in a more complete oxidation and long-term stability, while the AgNWs corrosion greatly decreases acetic acid production. This novel strategy for fabricating nanomaterial electrodes using AgNWs as a charge transfer conduit may stimulate insights into the design of nanomaterial electrodes.

Novel Flexible Ag/AgCl Quasi-Reference Electrode with Fishbone Nanowire Structure for Remarkable Potential Stability, Long-Term Reliability, and Noninvasive Electrocardiography.

The roadblocks for the planar silver/silver chloride (Ag/AgCl) quasi-reference electrode (qRE) development are the potential stability and long-term reliability as potentiometric sensors. Although there is a significant amount of work on potentiometric screen-printed and inkjet-printed sensors, none of the REs has comparable performance to that of the conventional glass RE and knowledge on reliable planar Ag/AgCl qREs is still limited. Here, a novel fishbone-structured flexible Ag/AgCl qRE (Fishbone-Ag/AgCl qRE) was developed and its stability and long-term reliability were significantly improved. The stability of the Fishbone-Ag/AgCl qRE was comparable to that of a commercial glass Ag/AgCl RE. In a long-term stability test, the Fishbone-Ag/AgCl qRE could continuously and stably operate for more than 4 h. Shelf-life testing revealed a 6 month life span. The conductivity and diameter of the nanowires in the fishbone structure of the Ag/AgCl qRE had important influences on electrochemical properties. The conductivity of the qRE influenced the charge-transfer rate in the electrode so that it affected the potential stability. Thicker diameter and slight chlorination on the surface of the AgNWs resulted in enhanced long-term reliability of the qRE. The capabilities of this new nanostructured material were applied in vivo for noninvasive monitoring of electrocardiogram. The discovery is elementary and substantially informs improved nanostructure RE design for testing and commercial medical device applications.

Cyclin A1 is expressed in mouse ovary.

Cyclin A1 belongs to the type-A cyclins and participates in cell cycle regulation. Since its discovery, cyclin A1 has been shown mostly in testis. It plays important roles in spermatogenesis. However, there were also reports on ovary expression of cyclin A1. Therefore, we intended to revisit the expression of cyclin A1 in mouse ovary. Our study showed that cyclin A1 was expressed at the mRNA level and the protein level in mouse ovary. Tissue staining revealed that cyclin A1 was expressed in maturating oocytes. With the recent data on the functions of cyclins in somatic and stem cells, we also discussed the possibilities of further studies of cyclin A1 in mouse oocytes and perhaps in the oogonial stem cells. Our findings not only add to the supportive evidence of cyclin A1 expression in oocytes, but also may promote more interest in exploring cyclin A1 functions in ovary.

Metastasis-associated 1 localizes to the sarcomeric Z-disc and is implicated in skeletal muscle pathology.

Metastasis-associated 1 (MTA1), a subunit of the nucleosome remodeling and histone deacetylation (NuRD) corepressor complex, was reported to be expressed in the cytoplasm of skeletal muscles. However, the exact subcellular localization and the functional implications of MTA1 in skeletal muscles have not been examined. This study aims to demonstrate the subcellular localization of MTA1 in skeletal muscles and reveal its possible roles in skeletal muscle pathogenesis. Striated muscles (skeletal and cardiac) from C57BL/6 mice of 4-5 weeks were collected to examine the expression of MTA1 by Western blotting and immunohistochemistry. Immunofluorescence and immunoelectron microscopy were performed for MTA1, α-actinin (a Z-disc marker protein), and SMN (survival of motor neuron) proteins. Gene Expression Omnibus (GEO) data sets were analyzed using the GEO2R online tool to explore the functional implications of MTA1 in skeletal muscles. MTA1 expression was detected by Western blotting and immunohistochemistry in skeletal and cardiac muscles. Subcellular localization of MTA1 was found in the Z-disc of sarcomeres, where α-actinin and SMN were expressed. Data mining of GEO profiles suggested that MTA1 dysregulation is associated with multiple skeletal muscle defects, such as Duchenne muscular dystrophy, Emery-Dreifuss muscular dystrophy, nemaline myopathy, and dermatomyositis. The GEO analysis also showed that MTA1 expression gradually decreased with age in mouse skeletal muscle precursor cells. The subcellular localization of MTA1 in sarcomeres of skeletal muscles implies its biological roles in sarcomere structures and its possible contribution to skeletal muscle pathology.

MicroRNA let-7b regulates neural stem cell proliferation and differentiation by targeting nuclear receptor TLX signaling.

Neural stem cell self-renewal and differentiation is orchestrated by precise control of gene expression involving nuclear receptor TLX. Let-7b, a member of the let-7 microRNA family, is expressed in mammalian brains and exhibits increased expression during neural differentiation. However, the role of let-7b in neural stem cell proliferation and differentiation remains unknown. Here we show that let-7b regulates neural stem cell proliferation and differentiation by targeting the stem cell regulator TLX and the cell cycle regulator cyclin D1. Overexpression of let-7b led to reduced neural stem cell proliferation and increased neural differentiation, whereas antisense knockdown of let-7b resulted in enhanced proliferation of neural stem cells. Moreover, in utero electroporation of let-7b to embryonic mouse brains led to reduced cell cycle progression in neural stem cells. Introducing an expression vector of Tlx or cyclin D1 that lacks the let-7b recognition site rescued let-7b-induced proliferation deficiency, suggesting that both TLX and cyclin D1 are important targets for let-7b-mediated regulation of neural stem cell proliferation. Let-7b, by targeting TLX and cyclin D1, establishes an efficient strategy to control neural stem cell proliferation and differentiation.

miR-451 protects against ischemic stroke by targeting Phd3.

Ischemic stroke still remains a therapeutic challenge due to its complex pathogenesis and implications. By screening biomarkers in the peripheral blood of ischemic stroke patients, miR-451 was identified as a differentially expressed miRNA along the disease course of ischemic stroke. To investigate the role of miR-451, middle cerebral artery occlusion (MCAO) was performed as an ischemic stroke model in mice. Intracerebroventricular administration of miR-451 mimic in the MCAO mice significantly decreased infarct size, while miR-451 inhibitor significantly increased infarct size. To understand the molecular mechanism of the protective effect of miR-451, Phd3 (also Egln3) was validated as a new miR-451 target. Either fewer or more Phd3-positive cells were observed in brain sections from mice receiving miR-451 mimic or inhibitor, respectively. In addition, the levels of p53 (a known Phd3 target) were significantly downregulated when the levels of Phd3 were reduced, suggesting its participation in reducing apoptosis after the miR-451 administration. Indeed, reduced apoptosis upon miR-451 mimic administration was detected by TUNEL staining. In conclusion, this study demonstrated a new protective role of miR-451 in cerebral ischemia and identified Phd3 as a novel miR-451 target, linking the mechanism to the involvement of p53 in the regulation of apoptosis during the pathogenesis of ischemic stroke.

ΜicroRNA-122 protects against ischemic stroke by targeting Maf1.

The protection of brain tissue against damage and the reduction of infarct size is crucial for improving patient prognosis following ischemic stroke. Therefore, the present study aimed to investigate the regulatory effect of microRNA (miR)-122 and its target gene repressor of RNA polymerase III transcription MAF1 homolog (Maf1) on the infarct area in ischemic stroke. Reverse transcription-quantitative PCR (RT-qPCR) was performed to determine miR-122 expression levels in an ischemic stroke [middle cerebral artery occlusion (MCAO)] mouse model. Nissl staining was conducted to measure the infarct area of the MCAO mouse model. Moreover, RT-qPCR was performed to investigate the relationship between the expression of Maf1 and miR-122 in the MCAO mouse model. Dual-luciferase reporter assay in vitro and miR-122 mimic or inhibitor treatment in vivo were conducted to verify that miR-122 targeted and inhibited Maf1 expression. The results suggested that miR-122 was upregulated in the brain tissue of MCAO model mice. miR-122 overexpression effectively reduced the size of the infarct area in comparison with a control and miR-122 knockdown in brain tissue resulted in the opposite effect. Moreover, Maf1 was confirmed to be a direct target of miR-122. The results of a dual-luciferase reporter assay indicated that miR-122 bound to the 3'-untranslated region of Maf1. Maf1 expression decreased after stroke model induction in comparison with that in sham animals, and Maf1 expression was negatively associated with the expression of miR-122. In addition, miR-122 knockdown increased Maf1 expression levels, whereas miR-122 overexpression decreased Maf1 expression levels in comparison with a control. In conclusion, the results suggested that miR-122 improved the outcome of acute ischemic stroke by reducing the expression of Maf1.

Application of short hydrophobic elastin-like polypeptides for expression and purification of active proteins.

To investigate the application of short elastin-like polypeptides (ELPs) in the purification of bioactive proteins, short hydrophobic ELP[I] n (n = 30, 40, 50) tags were constructed. Both the ELP[I] n tags and the ELP[I] n -Trx fusion proteins could be stably expressed in Escherichia coli and purified by inverse transition cycling, respectively. Total protein concentrations determined by BCA protein assay showed that the yield of the fusion proteins decreased with increasing ELP length. Measurements of the inverse transition temperature (T t) of the ELP[I] n -Trx under different salts or PEG8000 concentrations showed decreased T t upon elevated concentrations; while, all the T ts were suitable for generating proteins from 4 to 37.5 ºC. Furthermore, to identify a linker peptide for bioactive protein production without the need to remove the ELP[I] n tag, the activity of eGFP protein fused with ELP[I]30 tag by either a poly-N or a G4S linker was quantified using a fluorescence spectrophotometer. The results indicated that the ELP[I]30-eGFP fusion proteins with the poly-N linker showed higher fluorescence levels than those with the G4S linker. Our results demonstrated that short ELP[I] n tags with low T t were useful in protein expression and purification, and poly-N linker played the key role in producing bioactive proteins without the need to remove the ELPs.

Peptidoglycan recognition protein-S (PGRP-S) is upregulated by NF-kappaB.

Cerebral ischemia triggers inflammation and apoptosis, and the transcription factor NF-kappaB is a key regulator of both events. Here, we report on the induction of the peptidoglycan recognition protein-S (PGRP-S) in a mouse model of cerebral ischemia. Upregulation was reduced if the NF-kappaB subunit RelA was conditionally deleted in the brain. Regulation of PGRP-S transcription by RelA was confirmed in vitro. Cotransfection of a RelA expression plasmid stimulated the expression of a PGRP-S luciferase fusion gene. Mutation of two NF-kappaB response elements in the PGRP-S promoter disrupted stimulation by RelA. To investigate the function of PGRP-S in cerebral ischemia, we subjected PGRP-S(-/-) mice to cerebral ischemia. However, there was no difference in the infarct size in PGRP-S-deficient mice compared to controls. In summary, the data show that PGRP-S is induced in cerebral ischemia by RelA, but its role in ischemia is unclear.

Highly transparent and flexible circuits through patterning silver nanowires into microfluidic channels.

The development of flexible and transparent devices requires completely transparent and flexible circuits (TFCs). To overcome the disadvantages of the previously reported TFCs that are partially transparent, lacking pattern control, or labor consuming, we achieve true TFCs via a facile process with precise pattern control, exhibiting concurrent high transparency, conductivity, flexibility, stretchability, and robustness. A highly transparent and flexible conductive film is first made through spin coating silver nanowires (AgNWs) onto polydimethylsiloxane (PDMS), and demonstrates simultaneous high transparency (90.86%) and low sheet resistance (3.22 Ω sq-1). Taking advantage of microfluidic technology, circuits with ultraprecise and complex patterns from the microscale to milliscale are obtained through spin coating of AgNWs into microfluidic channels on PDMS. Without elaborate processing, this method may be suitable for mass production, which would contribute enormously to potential applications in wearable medical equipment and transparent electronic devices.

The influence of cell morphology on microfluidic single cell analysis.

Microfluidics has been widely used in single cell analysis. Current protocols allow either spread or round cells to be analyzed. However, the contribution of cell morphology to single cell analysis has not been noted. In this study, four proteins (EGFR, PTEN, pAKT, and pS6) in the EGFR signaling pathway are measured simultaneously using microfluidic image cytometry (MIC) in glioblastoma cells U87. The results show that the MIC technology can reveal different subsets of cells corresponding to the four protein expression levels no matter whether they are round or spread at the time of the measurements. However, sharper distinction is obtained from round cells, which implies that cellular heterogeneity can be better resolved with round cells during in situ protein quantification by imaging cytometry. This study calls attention to the role of cell morphology in single cell analysis. Future studies should examine whether differences in data interpretation resulting from cell morphology could reveal altered biological meanings.

Cancer-specific killing by the CD suicide gene using the human telomerase reverse transcriptase promoter.

Human telomerase reverse transcriptase (hTERT), the catalytic subunit of the telomerase, is transcriptionally upregulated in more than 90% of tumor cells. It may be used as a tool for driving a gene to kill tumors specifically. To test this idea, luciferase reporter gene was used and the results showed that hTERT promoter could restrict the gene expression in the telomerase-positive tumor cells. A tumor-specific expression plasmid phTERT-CD was constructed, in which the E. coli cytosine deaminase (CD) gene was controlled by the hTERT promoter. A colorectal cancer cell line (LoVo) and a normal amnion cell line (WISH) were transfected by this plasmid. It was shown that the expression of the CD gene increased the sensitivity of LoVo cells to the prodrug, 5-fluorocytosine (5FC), over 800-fold, while the sensitivity of WISH cells to 5FC was increased only 6-fold. Mixed cell experiments showed a strong "bystander effect" on CD-negative cells. Furthermore, a significant anti-tumor effect of the phTERT-CD/5FC system was observed in nude mice bearing mammalian carcinoma induced by s.c. inoculation of LoVo cells when the mice were given 250 mg/kg 5FC twice a day for 10 consecutive days. These results indicated that hTERT promoter could target the suicidal effect of CD gene to tumor cells, and therefore, may be a novel and promising targeting approach to the treatment of cancer.

High-intensity focused ultrasound leads to histopathologic changes of the inferior turbinate mucosa with allergic inflammation.

This study was aimed at understanding the histopathologic changes that occur in the nasal mucosa of patients with perennial allergic rhinitis after high-intensity focused ultrasound (HIFU) treatment. Biopsy specimens of the inferior turbinate mucosa were taken from 11 PAR patients before, immediately after and 1 y after HIFU treatment. Morphometric analysis revealed that the density of eosinophils and other inflammatory cells increased immediately after treatment and then were decreased significantly 1 y post-treatment. Submucosal glands were swollen and venous sinusoids were dilated, but there was no statistically significant change in their density, immediately after treatment. However, both glands and venous sinusoids significantly decreased in number 1 y after HIFU treatment. The ciliated epithelium or basement membrane of the nasal mucosa was well preserved at all stages. In conclusion, HIFU is a tolerable and effective treatment to reduce inflammation of the inferior turbinate mucosa in patients with perennial allergic rhinitis.

Calretinin is expressed in the intermediate cells during olfactory receptor neuron development.

The field of neurogenesis has greatly benefited from stage-specific marker discoveries. However, such markers are not well defined in the olfactory epithelium (OE), where olfactory receptor neurons (ORNs) are constantly generated throughout lifetime. During OE neurogenesis, there is a lack of markers that label cells that are at the intermediate stage before they are fully mature. In this study, we show that during embryonic development calretinin is expressed transiently in the intermediate cells right before ORNs become mature. Calretinin is expressed between the end of beta-III tubulin (an immature neuronal marker) expression and the beginning of olfactory marker protein (OMP, a mature neuronal marker) expression in ORNs. Therefore, calretinin can serve as a marker of the intermediate ORNs. With this discovery, future studies can use calretinin as a tool to define these intermediate ORNs during olfactory neurogenesis.

Dynamic Roles of microRNAs in Neurogenesis.

MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression at the post-transcriptional level by mediating mRNA degradation or translational inhibition. MiRNAs are implicated in many biological functions, including neurogenesis. It has been shown that miRNAs regulate multiple steps of neurogenesis, from neural stem cell proliferation to neuronal differentiation and maturation. MiRNAs execute their functions in a dynamic and context-dependent manner by targeting diverse downstream target genes, from transcriptional factors to epigenetic regulators. Identifying context-specific target genes is instrumental for understanding the roles that miRNAs play in neurogenesis. This review summarizes our current state of knowledge on the dynamic roles that miRNAs play in neural stem cells and neurogenesis.

Genome-wide profiling identified a set of miRNAs that are differentially expressed in glioblastoma stem cells and normal neural stem cells.

A major challenge in cancer research field is to define molecular features that distinguish cancer stem cells from normal stem cells. In this study, we compared microRNA (miRNA) expression profiles in human glioblastoma stem cells and normal neural stem cells using combined microarray and deep sequencing analyses. These studies allowed us to identify a set of 10 miRNAs that are considerably up-regulated or down-regulated in glioblastoma stem cells. Among them, 5 miRNAs were further confirmed to have altered expression in three independent lines of glioblastoma stem cells by real-time RT-PCR analysis. Moreover, two of the miRNAs with increased expression in glioblastoma stem cells also exhibited elevated expression in glioblastoma patient tissues examined, while two miRNAs with decreased expression in glioblastoma stem cells displayed reduced expression in tumor tissues. Furthermore, we identified two oncogenes, NRAS and PIM3, as downstream targets of miR-124, one of the down-regulated miRNAs; and a tumor suppressor, CSMD1, as a downstream target of miR-10a and miR-10b, two of the up-regulated miRNAs. In summary, this study led to the identification of a set of miRNAs that are differentially expressed in glioblastoma stem cells and normal neural stem cells. Characterizing the role of these miRNAs in glioblastoma stem cells may lead to the development of miRNA-based therapies that specifically target tumor stem cells, but spare normal stem cells.

TAK1 in brain endothelial cells mediates fever and lethargy.

Systemic inflammation affects the brain, resulting in fever, anorexia, lethargy, and activation of the hypothalamus-pituitary-adrenal axis. How peripheral inflammatory signals reach the brain is still a matter of debate. One possibility is that, in response to inflammatory stimuli, brain endothelial cells in proximity to the thermoregulatory centers produce cyclooxygenase 2 (COX-2) and release prostaglandin E2, causing fever and sickness behavior. We show that expression of the MAP kinase kinase kinase TAK1 in brain endothelial cells is needed for interleukin 1ß (IL-1ß)-induced COX-2 production. Exploiting the selective expression of the thyroxine transporter Slco1c1 in brain endothelial cells, we generated a mouse line allowing inducible deletion of Tak1 specifically in brain endothelium. Mice lacking the Tak1 gene in brain endothelial cells showed a blunted fever response and reduced lethargy upon intravenous injection of the endogenous pyrogen IL-1ß. In conclusion, we demonstrate that TAK1 in brain endothelial cells induces COX-2, most likely by activating p38 MAPK and c-Jun, and is necessary for fever and sickness behavior.

miR-137 forms a regulatory loop with nuclear receptor TLX and LSD1 in neural stem cells.

miR-137 is a brain-enriched microRNA. Its role in neural development remains unknown. Here we show that miR-137 has an essential role in controlling embryonic neural stem cell fate determination. miR-137 negatively regulates cell proliferation and accelerates neural differentiation of embryonic neural stem cells. In addition, we show that the histone lysine-specific demethylase 1 (LSD1), a transcriptional co-repressor of nuclear receptor TLX, is a downstream target of miR-137. In utero electroporation of miR-137 in embryonic mouse brains led to premature differentiation and outward migration of the transfected cells. Introducing a LSD1 expression vector lacking the miR-137 recognition site rescued miR-137-induced precocious differentiation. Furthermore, we demonstrate that TLX, an essential regulator of neural stem cell self-renewal, represses the expression of miR-137 by recruiting LSD1 to the genomic regions of miR-137. Thus, miR-137 forms a feedback regulatory loop with TLX and LSD1 to control the dynamics between neural stem cell proliferation and differentiation during neural development.

Human interleukin 10 gene therapy decreases the severity and mortality of lethal pancreatitis in rats.

BACKGROUND: Studies have proven the validity of interleukin-10 (IL-10) in the treatment of experimental pancreatitis. Prophylactic human IL-10 (hIL-10) gene treatment attenuated the severity in cerulein models. Our research aims to study whether the therapeutic hIL-10 gene could decrease both severity and mortality in a lethal pancreatic model. METHODS: Severe acute pancreatitis (SAP) was induced by sodium taurocholate. A plasmid-hIL-10 construct (pcDNA3-hIL-10) complexed with cationic liposomes was administered to SAP rats by a single intraperitoneal injection. Levels of hIL-10 in the pancreas, liver, and lungs were determined by ELISA kits. The severity of pancreatitis was assessed in terms of serum amylase, histology, and tissue tumor necrosis factor alpha (TNF-alpha). Mortality, observed for 7 days, was evaluated for gene therapy or control groups. RESULTS: After hIL-10 gene therapy, hIL-10 levels in the pancreas, liver, and lungs increased significantly and the serum amylase, tissue TNF-alpha, and histological changes in pancreas, liver, and lungs decreased markedly. Therefore, mortality was significantly reduced in the hIL-10 gene therapy group, in which 70% of rats survived in the 7-day observation, while only 10% survived in untreated groups (P < 0.05). CONCLUSION: We found that liposome/hIL-10 gene therapy decreased severity and mortality in SAP, even carried out after SAP establishment, predicting a more convenient shift to clinical applications.